Sirenophila cliffwetmorei is a species of saxicolous (rock-dwelling), crustose lichen in the family Teloschistaceae.

Its thallus can reach up to 1 centimetre in width, has a whitish to whitish-grey colour, and is very thin, sometimes almost merging with the substrate, and has paler edges with a darker grey centre.

Its numerous tiny apothecia (fruiting bodies) give the thallus a yellow-orange appearance.

The thallus is very thin, sometimes almost merging with the underlying substrate (endophloeodal), and tends to be paler around the edges, with a darker grey hue near the centre.

[3] The apothecia of Sirenophila cliffwetmorei are the most prominent feature of this species, and give the entire thallus a yellow-orange appearance.

The discs of the apothecia are usually slightly concave or flat and have a dull orange to brownish colour, often covered with a yellow pruina.

The hymenium stands at about 80 μm in height and the epihymenium is brownish-orange, turning gradually brownish when treated with a solution of potassium hydroxide (K).